Uniformly-shaped particulate resins can be used for various purposes such as electrophotographic toners, spacers for use in liquid crystal panels, colored particles for use in electronic papers, and carriers for use in medicines. Specific examples of the method for producing such uniformly-shaped particulate resins include methods in which a uniformly-shaped particulate resin is produced by making a reaction in a liquid, such as soap-free polymerization methods. Soap-free polymerization methods have advantages such that a particulate resin having a relatively small particle diameter and a sharp particle diameter distribution can be produced; and the particle form is nearly spherical, but have problems to be solved such that a long time, and large amounts of water and energy are used for producing a particulate material because it takes time to perform such a polymerization reaction, it takes time to remove a solvent (typically water) from the liquid in which the reaction is performed, resulting in deterioration of production efficiency, and various processes such as a process for separating the resultant particulate material, and processes for washing and drying the particulate material after producing the particulate material in the liquid have to be performed.
In attempting to solve the problems mentioned above, some of the present inventors and other inventors have proposed toner production methods using an ejection granulation method in JP-2008-286947-A and JP-2011-197161-A. Specifically, the toner production methods use a droplet ejector for ejecting droplets of a toner composition liquid, which is a raw material of a toner. The droplet ejector has a thin film, which has multiple nozzles and which is periodically vibrated up and down by an electromechanical converter serving as a vibrator to periodically change the pressure in a chamber, which contains the toner composition liquid and which includes the thin film having the Multiple nozzles as a constitutional member, thereby ejecting droplets of the toner composition liquid from the nozzles to a space present below the nozzles. The thus ejected droplets of the toner composition liquid naturally fall through the space and proceed in the same direction, thereby forming lines of droplets of the toner composition liquid. In this regard, the ejected droplets are reshaped so as to be spherical due to the difference in surface tension between the toner composition liquid and air in the space. The reshaped droplets are then dried, resulting in formation of a particulate toner.
In addition, JP-2011-197161-A also discloses a method for cleaning the nozzle surface to which the toner composition liquid is adhered. The cleaning method uses a cleaning liquid ejector which is arranged so as to be opposed to the nozzle surface and which ejects a cleaning liquid toward the nozzle surface to clean the nozzle surface.
In the toner production methods mentioned above, there is a case where the toner composition liquid exudes from the nozzles, and therefore the toner composition liquid is adhered to the nozzle surface, or a case where the ejected droplets of the toner composition liquid fly back to the nozzle surface. The toner composition liquid thus adhered to the nozzle surface is solidified with time, and in addition the toner composition liquid is further adhered to the solidified toner composition, resulting in enlargement of the toner composition block on the nozzle surface (i.e., smudges are formed on the nozzle surface). In this case, there is a possibility that air turbulence is formed in the space located below the nozzles due to the toner composition block, thereby uniting droplets of the toner composition liquid ejected by the nozzles, resulting in broadening of the particle diameter distribution of the resultant toner and deterioration of productivity of the toner. Therefore, it is preferable to periodically clean the nozzle surface.
When smudges formed on the nozzle surface are removed by the cleaning method disclosed in JP-2011-197161-A, in which a cleaning liquid is sprayed to the nozzle surface, it takes time until the smudges are softened by the cleaning liquid. Alternatively, when the cleaning operation is repeated several times to soften the smudges, the cleaning time is relatively long. In addition, when a cleaning liquid is sprayed and the cleaning liquid is adhered to smudges, part of the cleaning liquid adhered to the toner composition block drips from the block, and therefore it is hard to sufficiently clean the nozzle surface. This problem is not limited to the toner production apparatus, and occurs in inkjet recording apparatus. Specifically, in inkjet recording apparatus, droplets of an inkjet ink are ejected from nozzles so that the droplets are adhered to a recording medium, resulting in formation of an image on the recording medium. In such inkjet recording apparatus, the ink is often adhered to the nozzle surface and then dried, thereby forming an ink deposit around the nozzles. When a part of the ink deposit blocks a nozzle, the shape of the nozzle is changed, and thereby the ejection direction of droplets ejected from the nozzle is changed (i.e., the positions of the recording medium to which the droplets are adhered are changed), resulting in deterioration of the image quality.